Researchers at North Carolina (NC) State University have developed elastic, touch-sensitive fibers with the ability to interface with electronic devices.
Michael Dickey, a professor of chemical and biomolecular engineering at NC State and the author of the study says, “We have created soft and stretchable fibers that can detect touch, as well as strain and twisting. These microscopic fibers may be useful for integrating electronics in new places, including wearable devices.”
The fibers are made of tube-like polymer strands that contain a liquid metal alloy, eutectic gallium and indium (EGaIn). The strands are only slightly thicker than a human hair. Each fiber consists of three strands: one is completely filled with EGaIn, one is two-thirds filled with EGaIn, and one is only one-third filled with EGaIn. Then the tubes are twisted together into a tight spiral.
The touch-sensitive fibers work because of capacitance, which is when an electric charge is stored between two conductors separated by an insulator. When a finger touches the fibers, it changes the capacitance between the finger and the EGaIn inside the insulating polymer strands. As the finger moves along the fiber, the capacitance varies depending on how many strands contain EGaIn at that point in the fiber. This gives the wearer the ability to send different electronic signals depending on which part of the fiber is touched.